Effects of heating on the mechanical and chemical properties of human dentin.
Effects of heating on the mechanical and chemical properties of human dentin.
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DOI：
10.1016/j.dental.2011.11.015
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发表时间：
2012-04
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影响因子：
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通讯作者：
M. Hayashi;Y. Furuya;K. Minoshima;M. Saito;K. Marumo;S. Nakashima;C. Hongo;Jongduk Kim;T. Ot
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文献类型：
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作者：
M. Hayashi;Y. Furuya;K. Minoshima;M. Saito;K. Marumo;S. Nakashima;C. Hongo;Jongduk Kim;T. Ot
我们之前发现，人类牙本质的弯曲和拉伸强度在加热到140°C后增加了2-2.4倍，并推断出更高密度结构的产生以及脱水可能促进了强度的增加。我们的测试假设是，管间牙本质，这构成了有机成分的主要组成部分，是选择性地受到加热的影响，这种变化可能发生没有严重损害的基本结构的牙本质I型collagen. METHODS的人牙本质的微观力学变化，在140°C加热进行了研究。通过X射线衍射、显微傅里叶变换红外光谱、透射电镜和透射电镜研究了加热后牙本质胶原的化学变化。显微红外光谱（micro-FTIR）和激光拉曼光谱分析，以及高效液相色谱交联分析。纳米压痕测试结果表明，在140°C加热后，管间牙本质的显微硬度增加到未加热牙本质的1.8倍;另一方面，管周牙本质没有变化。X射线衍射结果表明，加热后胶原分子的横向堆积量由13.6±0.3收缩到10.6±0.1 μ m，再水化7天后胶原分子的横向堆积量又恢复到原来的水平。加热后，通过微型傅里叶变换红外光谱、拉曼分析或交联分析进行的测试中，胶原蛋白分子没有检测到实质性的化学变化。意义这些结果表明，含有大部分I型胶原蛋白的管间牙本质受到选择性影响140°C加热对其胶原蛋白没有严重损害。
OBJECTIVESWe had previously discovered that the flexural and tensile strengths of human dentin were 2–2.4 times greater after being heated to 140°C, and deduced that the generation of higher-density structures and therefore dehydration probably promoted the increased strength. Our test hypotheses were that intertubular dentin, which constitutes a major part of organic components, was selectively affected by heating, and such changes could happen without critical damages to the basic structure of dentin type I collagen.METHODSMicro-mechanical changes of human dentin by heating at 140°C were investigated by nano-indentation. Chemical changes in dentin collagen after heating were also investigated by X-ray diffraction study, a microscopic Fourier transform infrared (micro-FTIR) and a laser Raman spectroscopic analyses, and a cross-linking analysis by high-performance liquid chromatography.RESULTSThe results of nano-indentation showed that the micro-hardness of intertubular dentin increased after heating at 140°C to 1.8 times more than unheated dentin; on the other hand, peritubular dentin was unchanged. Results of X-ray diffraction showed that the lateral packing of collagen molecules shrank from 13.6±0.3 to 10.6±0.1Å after heating, but the shrinkage reversed to the original after rehydration for seven days. After heating, no substantial chemical changes in the collagen molecules were detected in tests by micro-FTIR or Raman analyses, or by cross-linking analysis.SIGNIFICANCEThese results suggest that intertubular dentin, which contains most of the type I collagen, was selectively affected by heating at 140°C without critical damage to its collagen.